1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to an image display apparatus and method, and more particularly, to an image display apparatus and method which can reduce the power consumption of an image display apparatus and ensure the visibility of images in response to user input for performing power control according to variations in the intensity of external illumination.
2. Description of the Related Art
In general, the power consumption of a display module that displays images accounts for much of the power consumed in an entire image display device.
Recently, image display devices equipped with a display module that supports colors have been commercialized. Display modules that support color images generally consume more power than display modules that support black-and-white images.
Display modules are largely classified into self-emission display modules which can generate light without the aid of additional devices and non-emission display modules which need additional devices such as backlight units to generate light.
A user may change the lightness of a display device according to the intensity of external illumination while watching images displayed by the display device. In this case, the visibility of images displayed by the display device may deteriorate because the change of the lightness of the display device does not reflect various image properties that affect the visibility of the display device, for example, lightness, luminance, contrast, chroma, etc. Also, since the change of the lightness of a display device is generally performed by processing image signals, the power consumption of a display device is rarely taken into consideration when changing the lightness of the display device. Given that most image display devices are compact-sized and portable, it is highly important to develop image display devices that can ensure the visibility of images while consuming less power.
Korean Patent Laid-Open Gazette No. 2004-0054118 discloses a method of controlling the power of a mobile communication terminal which can reduce waste of power and increase the lifetime of batteries by predefining a high-quality item, determining whether input data is associated with the predefined high-quality item, controlling lightness for the input data to be a backlight lightness for the predefined high-quality item if the input data is determined to be associated with the predefined high-quality item, and controlling the lightness for the input data to be a backlight lightness for a predefined low-quality item. This method, however, does not specify how to minimize the power consumption of a display device according to the intensity of external illumination while ensuring the visibility of images.
In addition, Japanese Patent Laid-Open Gazette No. 2001-125063 discloses a method of driving a liquid crystal display (LCD) device which involves increasing the luminance of a backlight unit when there are variations in the intensity of ambient illumination (e.g., outdoor or indoor illumination) and compensating the gamma, luminance, and hue of image signals according to the increase in the luminance of the backlight unit. This method includes compensating visibility according to variations in the intensity of external illumination, but does not specify how to compensate an image according to the intensity of external illumination while reducing the power consumption of a display device.